Reproducer for disc-shape storage medium

ABSTRACT

A reproducer provided with a vibration value measuring means which has functions of, prior to data reproducing, detecting vibration of, and determining vibration value for, a disc, and which measures a vibration value obtained when the disc with a known mass eccentricity is mounted on the reproducer and is rotated, characterized in that values relating to the measured vibration value are stored in a storage in the reproducer as threshold values indicating allowable limits of the vibration value, thereby preventing unstable vibration detection due to differences between individually manufactured reproducers when a disc with a large mass eccentricity is reproduced at high speed, and permitting a reproducing operation that will not give a user an unpleasant feeling.

This application is a 371 of PCT/JP00/01926, filed Mar. 29, 2000.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a device for reproducing data from aCD-ROM or like storage medium.

BACKGROUND OF THE TECHNOLOGY

As is disclosed in Japanese Laid-Open Patent No. Hei 10-83615, forexample, data is generally read out by first measuring vibration valueby rotating a disc at a maximum speed prior to reproducing data and,when the vibration value is beyond a predetermined threshold level, byrotating the disc at a speed lower than the maximum speed. A CD-ROM is aCD (compact disc) used as a ROM (read-only memory) and is used incomputer systems just like a semiconductor ROM. As high speed processingis required in computer systems, rotational speed of a CD-ROM isgenerally set at a speed several to several tens of times higher thanthe rotational speed (200 rpm) of audio CD's.

When a CD-ROM is scanned by a disc reproducer at such a high speed as 40times the standard scanning speed, for example, an error of a trackingcontrol system for correcting eccentricity of track due to discvibration increases thus resulting in an error in reading-out data onthe disc and requiring a retrial thereby lowering performance ofreproduction. Also, when a low-quality disc having a large masseccentricity is rotated, not only the disc but also the entire discreproducer vibrates, and the vibration affects a hard disc drive (HDD)installed in a housing of a computer system together with the discreproducer. There is thus a possibility of causing read/write error inthe HDD, which lowers reliability of the entire computer system. Also,even if an error may not be generated in reading/writing of the HDD,vibration of the disc reproducer gives an unpleasant feeling to a user.The above problem can be solved by either reducing mass eccentricity ofthe CD-ROM or lowering the rotational speed. However, in practice, thereis a large dispersion in the quality of CD-ROM's and some discs areinappropriate for reproduction at a high speed.

In order to solve this problem, vibration value of a disc reproducer isdetected and, when the detected value is beyond a preset thresholdlevel, the reproducer is operated at a reduced disc rotational speed.However, as the detected vibration value varies due to manufacturingdispersion of individual disc reproducers, in a conventional fixedthreshold level design, there has been a problem of inability toprecisely switching the disc rotational speed.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a disc reproductionmethod and device that can stably reproduce data at as high speed aspossible for both a high-quality storage medium disc and low-qualitystorage medium disc. Also, the present invention employs a method ofdetecting the maximum data reproducible speed by performing vibrationdetection from the side of a lower disc speed in order not to give anunpleasant feeling to a user by generating large vibration even during avibration detecting mode.

In order to achieve the above object, the data reproducer in accordancewith the present invention comprises the following: namely, discrotating means structured in a manner such that a storage medium dischaving data recorded on a spiral or concentric track and a center holecan be detachably fit to a spindle of the reproducer, a signal converterfor reading out the data from the disc, and moving means for moving thesignal converter in the radial direction of the disc.

Next, an allowable-limit vibration value is set in an adjusting processof individual data reproducer manufacture, and a plurality ofallowable-limit mass eccentricity discs (hereinafter referred to as“standard vibrating discs”) with a known mass eccentricity is preparedof which the vibration values at the maximum data reproduction speed andlower data reproduction speeds are equivalent to the allowable-limitvibration value. Each of the discs is then mounted and the difference(P—P value) between the peak value in the positive direction of atracking servo error signal (TE signal) and the peak value in thenegative direction as obtained by rotating at a predeterminedreproduction speed is detected as the vibration value of the discreproducer in question, and the vibration value is set as the thresholdlevel for the combination of the data reproduction speed and thevibration-limit disc as described later. When a disc with an unknownmass eccentricity is mounted, vibration value is detected at a datareproduction speed on the lower speed side that is lower than themaximum reproduction speed (hereinafter simply referred to as “the lowspeed side”, the opposite side being referred to as “the high speedside”), followed by a first step of measuring a voltage (hereinafterreferred to as “vibration value”) proportional to the disc vibrationthat is occurring and a second step of judging whether or not thevibration value is below the threshold level. When it is judged in thesecond step that the vibration value is below the threshold level, thedisc is rotated at the above-mentioned reproduction speed by the discrotating means, and the signal converter reads out the data from thedisc. When it is judged that the mass eccentricity is not within theallowable range, the disc is rotated by the disc rotating means at adata reproduction speed lower than the vibration detecting speed so thatthe afore-mentioned data can be read out from the disc with the signalconverter.

In other words, a plurality of vibration detecting speeds (which may bethe same as the data reproduction speed) is set at the maximum datareproduction speed and at speeds lower than that, and an allowable-limitmass eccentricity disc (standard vibrating disc) is prepared for each ofthe detecting speeds. The first threshold level for the first vibrationdetecting speed is set at the vibration value as detected on anallowable-limit mass eccentricity disc Da at a first vibration detectingspeed. When a disc D with an unknown mass eccentricity is mounted, ifthe detected vibration data at the first vibration detecting speed iswithin the range of the first threshold level, vibration detection iscarried out at a second vibration detecting speed that is higher thanthe first vibration detecting speed.

The second threshold level for the second detection speed is set at thevibration data as detected on an allowable-limit vibrating disc Db at asecond speed. When the detected vibration data at the second vibrationdetecting speed of the disc D with an unknown mass eccentricity iswithin the range of the second threshold level, vibration detection at athird vibration detecting speed is carried out. In this way, vibrationdetection is carried out in sequence from the low-speed side toward thehigh-speed side. At the stage a detected vibration data is found to beoutside of respective threshold level range, the data is read out with avibration detecting speed lower than the vibration detecting speed atwhich the detected vibration value was outside of respective thresholdlevel range as the maximum speed. A data reproducer having such datareading means is hereby proposed.

According to a reproducer having the above structure, an allowable masseccentricity of a disc is precisely set as a threshold level (allowablerange) for each individual disc reproducer at the time the disc isreproduced at the maximum rotational speed at which data isreproducible. Consequently, by changing the maximum speed at which datacan be reproduced depending on the mass eccentricity, it becomespossible to carry out high-speed reproduction of a disc that has a smallmass eccentricity at the maximum speed available with the datareproducer, and to carry out reproduction of a disc having a large masseccentricity under a condition in which a problem associated with masseccentricity will not occur.

Also, according to the present invention, as high-speed rotation of alow-quality disc can be prevented, vibration value of a disc or datareproducer is limited. As a result, ripple effect of vibration on aseparate device (HDD, for example) contained in the same housing as thatof a data reproducer according to the present invention can be limited,thus enabling normal operation of the separate device (HDD, forexample). Also, as vibration of the disc or data reproducer is limited,unpleasant feeling to a user will be reduced.

Furthermore, in the present invention, as the maximum reproduction speedthat is available within the allowable limit of the vibration value isdetermined by carrying out vibration detection two or more times fromthe low speed side of the disc rotation toward the high speed side,unpleasant feeling to the user can be prevented in the vibrationdetecting mode, too.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a disc-shape storage medium (e.g., CD-ROM)drive in an exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing disc, optical pickup, tracking servocircuit, focus servo circuit, and read-out output circuit in FIG. 1.

FIG. 3 is a flow chart for vibration detection.

FIG. 4 is an equivalent block diagram that illustrates mass eccentricitymeasurement and disc speed setting means in system control block 11 inFIG. 1.

FIG. 5 is a flow chart for vibration data read-out process.

FIG. 6 is a flow chart for vibration threshold level changing process.

FIG. 7 is an external view of a reproducer in which EEPROM isincorporated in an IC card.

FIG. 8 is a graph showing relationship between disc rotational speed andvibration value.

FIG. 9 is a graph showing relationship between vibration detecting speedand allowable-limit vibration value.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description of a disc reproducer will be given in reference to FIGS. 1to 7 as an exemplary embodiment of the present invention. FIG. 1 showshost computer 1 and disc reproducer 2. Disc reproducer 2 functions as asource of data supply to host computer 1, and they are connected withbus 3.

Disc reproducer 2 comprises optical storage medium disc (CD-ROM) 4comprising a CD, disc-rotating spindle motor 5M and spindle drive 5D ofthe spindle motor both being part of disc rotating means, optical pickup6 as a signal converter, pickup drive 7 having a function as means forpositioning or moving optical pickup 6, waveform-shaping circuit 8 foramplifying and shaping signal picked up by optical pickup 6, servoprocessor 9 for moving and focusing pickup 6 and for controllingsynchronous rotation of motor 5M, signal processor block 10, systemcontrol block 11, and EEPROM 51 for storing threshold level.

Servo processor 9 comprises spindle servo block 12 as rotation controlmeans for disc 4, servo block 13 of drive block 7 of tracking servo,focus servo, and pickup 6, synchronization detection and demodulatingcircuit 14, and interface 15 for a microprocessor for interfacing withsystem control block 11. Signal processing block 10 comprises errordetection and correction circuit 16 and interface circuit 17.

System control block 11 comprises microprocessor 18M, program ROM 18Pfor storing executive instruction and the like for microprocessor 18M,work RAM 18R for microprocessor 18M, and clock generator 18C.

Disc (CD-ROM) 4 has center hole 20 to which spindle 19 coupled withmotor 5M is to be inserted, and has spiral track 41 that runs from theinner side of the disc toward the outer side with center hole 20 at thecenter as illustrated in FIG. 2. Data is recorded on track 41 as opticalpits of a number of data blocks in the known format, where 2352 bytesconstitute 1 unit or 1 data block, 1 byte being 8 bits. One data blockis reproduced in {fraction (1/75)} second when reproduced at a standardspeed that is the same as the scanning speed (1.2 to 1.4 m/sec) of anaudio CD. As is well known, CD-ROM data is reproduced at a constantangular velocity (CAV).

As schematically shown in FIG. 2, optical pickup 6 is a known unitcomprising, for example, laser source 61 comprising a laser diode,diffraction grating 62, beam splitter 64, collimater lens 66 forobtaining a parallel light beam, quarter-wavelength plate 67, objectivelens 68L, cylindrical lens (a lens looking like a part of a cylinder)disposed on the optical path of a reflected light beam, optical detector69 (consisting of 69F and 69B), actuator 68T for tracking control, andactuator 68F for focus control.

In optical pickup 6, focus actuator 68F is driven by a control signalfrom focus servo block (focus error detecting circuit 32, phasecompensation and drive circuit 33) that constitutes pickup servo block13, and a light beam emitted by light source 61 is focused withobjective lens 68 and projected to the main surface of disc 4, and thedata stored on disc 4 in the form of optical pits is read out. As theoptical pits are disposed on track 41 in a manner corresponding to thedata, when a non-modulated light beam is projected onto disc 4 as areproducing beam, the reproducing beam is modulated by the pits (data)and reflected light beam 64 incident on optical detector 69 becomes amodulated beam. Optical detectors 69F, 69B are optical detecting meansfor converting light into electric signals.

The tracking servo circuit and focus servo circuit that constitutepickup servo block 13 are publicly known as disclosed in JapaneseLaid-Open Patent Application No. Hei-83615, for example.

The vibration of a disc reproducer due to mass eccentricity of disc 4 asreferred to in the present invention takes place in principle in theradial direction of the disc, where the magnitude is proportional to theproduct of the amount of mass eccentricity and square of rotationalspeed of the disc, and its main component is one that is periodicallyproduced in each rotation of the disc.

In FIG. 2, tracking servo circuit 13T that constitutes pickup servoblock 13 detects radial displacement (in a direction crossing the track)of light beam spot 42 on track 41 as a TE signal with tracking-errordetecting circuit 31. Subsequently, negative feedback control is carriedout with phase compensation and drive circuit 30 to drive objective lens68L in the radial direction of the disc (direction crossing the track)by means of tracking actuator 68T, namely, in the direction of arrow68L, thus enabling tracing of the track.

Consequently, the TE signal contains vibration information even in thevibration data read-out mode.

Also, waveform-shaping circuit 8 demodulates EFM (Eight-to-FourteenModulation) signals into NRZ digital signals, for example, by using async signal obtained by connecting to sync detection and demodulationcircuit 14, and supplies them to servo processor 9.

Well-known error detection and correction circuit 16 connected to syncdetection and demodulation circuit 14 detects error in the demodulateddata (reproduced data) and makes correction when error is detected andis correctable. Error detection and correction circuit 16 is connectedto interface circuit 17 and system control block 11. In the event anuncorrectable data reproduction error has occurred, retrial is carriedout in a well-known manner. In the meantime, waveform-shaping circuit 8,sync detection and demodulation circuit 14, and error detection andcorrection circuit 16 can be collectively called reproduction signalprocessing means.

Also, interface circuit 17 is connected between error detection andcorrection circuit 16 and host computer 1 as well as between hostcomputer 1 and system control block 11.

Though not shown in FIG. 1, a frequency signal generator (hereinafterFG) is coupled to motor 5M and generates pulses at a frequencycorresponding to the rotation of motor 5M. FG is connected to systemcontrol block 11 and to spindle servo block 8 that executes CAV control.The output pulses of FG are not only used for CAV control but also forsetting time required for detection of vibration value of disc 4.Consequently, FG can be regarded as part of the vibration valuedetecting means. System control block 11 as reproduction control meanscomprises microprocessor 18M, program ROM 18P, and work RAM 18R, andoperates according to an operation control program stored in program ROM18P.

FIG. 4 is a block diagram illustrating a part of system control block 11and servo processor 9 in FIG. 1 in an equivalent or functional manner.As is clear from FIG. 4, system control block 11 and servo processor 9include mode switching signal generating means 96 and vibration valuedetecting and judging means 90 that further includes frequency divider93, comparing means 94, A/D converter 91, maximum value detecting means92, threshold-level generating means 95 and comparing means 94, andspeed command data generating means 97 for commanding the rotationalspeed of motor 5M.

Mode switching signal generating means 96 generates vibration valuedetecting mode signal, normal reproduction mode signal, andthreshold-level setting mode signal.

A/D converter 91 in FIG. 4 converts a TE signal voltage in pickup servoblock 13 into a digital signal when in vibration detecting mode. Maximumvalue detecting means 92 detects maximum amplitude value (Peak-to-Peakvalue) of the TE signal within the time of one rotation of disc 4 basedon signal 5S that indicates one rotational period of disc 4 as obtainedby frequency division of FG pulse 5F with frequency divider 93 and TEsignal 36D as obtained from A/D converter 91. Here, the vibration valueof disc 4 can be known from the difference between the positive peak andnegative peak of the TE signal, namely, the interval between thepositive peak and negative peak. In other words, if there is novibration of disc 4, it is not necessary to adjust tracking of lightspot 42 based on vibration, and the voltage of the TE signal is in thevicinity of zero volt under normal servo condition. On the other hand,when there is vibration due to mass eccentricity of a disc, the positionof the objective lens in the radial direction of disc 4 changes greatly,and the voltage of the TE signal changes toward positive or negativedirection in order to make correction. Accordingly, it becomes possibleto measure vibration as eccentricity of a track in terms of the TEsignal. In this exemplary embodiment, vibration is detected based on thesum of the maximum value of the positive peak and the maximum value ofthe negative peak of the TE signal voltage during one rotation of disc4, namely, the amount of amplitude change from the maximum value of thepositive peak to the maximum value of the negative peak. Threshold-levelgenerating means 95 sends out to first judging means, namely, comparingmeans 94 a signal, namely, threshold level Vr that indicates allowablelimit of vibration when disc 4 is rotated at the maximum speed. Thethreshold level Vr is a criterion value pre-stored in EEPROM 51, whichis read out from EEPROM 51 by writing/reading (hereinafter R/W) controlmeans 52, and is sent to comparing means 94 through threshold-levelgenerating means 95. Comparing means 94 makes judgment as to whether ornot the maximum value of the TE signal that indicates vibration value isbelow the criterion value, and sends the result to speed command datagenerating means 97. When the vibration value exceeds threshold levelVr, a low-quality disc flag is set and the disc rotational speed islowered.

In FIG. 4, speed command data generating means 97 puts out at least twospeed command data to line 98, namely, a maximum speed and a secondspeed lower than the maximum speed. When a maximum speed command is putout from speed command data generating means 97, spindle servo block 12drives disc 4, and the focus servo circuit and tracking servo circuitare brought into operation. Under a state of data reproduction, signal36D obtained by digitalizing TE signal 36 is put to maximum valuedetecting means 92. By obtaining periodic signal 5S for one rotation ofa disc by frequency division of FG signal 5F, maximum amplitude valueVte during one rotation of the disc is obtained, comparison is made bycomparing means 94 to determine whether or not Vte is within theallowable range, namely, less than the threshold level Vtr. When a “No”signal is obtained indicating that Vte>Vtr, an assumption is made thatthe disc is of low quality, rotational speed of disc 4 is lowered fromthe maximum speed to the second speed, and date reproduction is carriedout.

When a “Yes” signal is obtained indicating that Vte<Vtr, an assumptionis made that the disc is within the allowable range, and it is rotatedat the maximum speed as it is, and data reproduction is carried out. Asa result, the time required for data reproduction can be shortened.

In the above, a conceptual description is given on two cases of speed,namely, the maximum speed and a second speed lower than the maximumspeed. It is an object of the present invention to minimize as much aspossible the vibration that is unpleasant to a user even during thevibration detecting mode.

In other words, it is an object to find out a maximum speed for a discwith an unknown mass eccentricity at which secure data reproduction ispossible at or below an allowable vibration value. That is, for a dischaving a large vibration value, to detect the maximum speed at whichdata is reproducible on the low speed side where the vibration value isless than the allowable-limit vibration value of the reproducer, and,for a disc having a small vibration value, to detect the maximum speedat which data is reproducible on the high speed side.

This approach makes it possible to avoid reduction in performance of thereproducer due to a situation in which reproduction speed is set on thelow speed side for a disc having a small vibration value.

A description of operation of an exemplary embodiment of the presentinvention will now be given in reference to FIG. 8. The abscissa of thegraph of FIG. 8 represents disc rotational speed of a reproducer, whichcan be set in a manner such that data reproduction at ×10 (10 times),×12, ×20, and ×24 the standard speed can be made. The speeds of ×12,×20, and ×24 are also set as vibration detecting speeds. The ordinaterepresents vibration value and the values Aa, Ba, Ca on the ordinateaxis represent respective vibration values of allowable-limit discs Da,Db, Dc at ×12, ×20, and ×24 speeds. As shown in FIG. 8, the vibrationvalue increases in the order of Da, Db, Dc. These values are used asthreshold levels at each respective speed. Curves A, B, C show speed vs.vibration value characteristic of discs Da, Db, Dc.

Next, a description will be given below on the method of finding themaximum speed for data reproduction by detecting vibration value of adisc with an unknown mass eccentricity. First, vibration value isdetected at the moment the disc rotational speed has reached ×12 speedfrom a low speed. Supposing that the vibration value is detected to beV12, if V12>Aa, the disc is judged to be outside of the allowable limit.As a result, a minimum data reproduction speed (×10 speed in this case)can be set at which most of the vibration of disc reproducers will fallbelow the allowable limit when dispersion of mass eccentricity of discson the market is taken into account. In the case of the figure, as ×10speed is set as the minimum speed, the ×10 speed is set as the maximumspeed at which data is reproducible.

If V12<Aa. data reproduction at ×12 speed is judged to be possible.Additionally, a command is issued to increase the disc rotational speedto ×20 speed and the vibration value at the moment the disc rotationalspeed has reached ×20 speed is detected as V20 in the same manner asbefore.

If V20>Ba, the disc is judged to be outside of the allowable limit and aspeed change command is issued to lower the disc rotational speed to ×12speed, thus making the ×12 speed the maximum speed at which data isreproducible.

Furthermore, if V20<Ba, judgment is made that data reproduction ispossible at a further higher speed, and a command to increase the discrotational speed to ×24 speed is issued. At the moment the discrotational speed has reached ×24 speed, vibration detection is carriedout and detected value V24 is obtained as the vibration value in thesame manner as above.

If V24>Ca, the disc is judged to be outside of the allowable limit, arotational speed change command is issued to lower the disc rotationalspeed to ×20 speed, and the ×20 speed is set as the maximum speed atwhich the disc is reproducible.

If V24>Ca, judgment is made that data reproduction at ×24 speed ispossible and the ×24 speed is set as the maximum speed. By settingmaximum speed of data reproduction in the manner described above, itbecomes possible to set the maximum speed at which data is reproduciblewithout allowing vibration that exceeds the allowable vibration limit totake place on the high-speed side independently of the magnitude of discvibration values.

In other words, data reproduction on the high-speed side is enabled assurely as possible even for a disc with a small mass eccentricity, andpreviously mentioned functional reduction can be prevented.

Also, instead of making judgment by successively increasing thevibration detecting speed from the low-speed side as described above,vibration value Aa1 in FIG. 8 of an allowable-limit disc is chosen as athreshold level at 12× speed. If a vibration value V12 of a disc with aknown vibration value as obtained by reproducing at ×12 speed satisfiesV12<Aa1, it can be assumed that the vibration value is below theallowable limit at a maximum speed of ×24, and the ×24 speed is judgedto be the maximum reproduction speed. If Aa1<V12<As is satisfied, ×20speed is judged to be the maximum reproduction speed while, when V12<Asis satisfied, ×10 speed is judged to be the maximum speed. If thesensitivity of vibration detection is high enough, one-time vibrationdetection will suffice indicating that it is simpler than a method ofmaking judgment by successively increasing vibration detecting speedfrom the low speed side.

By setting threshold levels and making vibration value detection on thelow speed side as has been described above, the present invention hasadvantages of not giving an unpleasant feeling to a user duringvibration value detection and also avoiding the risk of possible damageof a computer system due to abnormal vibration that might be generatedwhen carrying out vibration value detection on the high speed side fromthe beginning using a disc having a large vibration value.

In recent data reproducers, data reproduction speed has increased suchas ×8, ×10, ×20, ×30, ×40 speeds, and there are many cases where datareproduction is carried out at respective speeds. In comparison to thesedata reproducers, the present invention provides a method in which amaximum reproduction speed applicable for a disc with an unknownvibration value can be determined in a stable and efficient manner.

A description of the above vibration detection operation will be givenin reference to the flow chart of FIG. 3. In the flow chart of FIG. 3,vibration detection starts when a disc with an unknown vibration valuehas been mounted, namely, when disc 4 has started to rotate and opticalpickup 6 has detected a signal. A command for ×12 speed at which thedisc rotational speed is higher than the lowest data reproduction speedset in the disc reproducer is sent to speed command data generatingmeans 97. At the moment ×12 speed is reached, vibration value data V12,namely TE signal (2-byte numeral), is input to microprocessor 18M ofsystem control block 11 as an output of maximum value detecting means 92as described earlier. Vibration value data V12 is then compared with athreshold level Aa (stored in EEPROM 51) to determine whether vibrationvalue data V12 is greater or smaller. When vibration value data V12 isgreater than the threshold level Aa, ×10 speed is judged to be the speedat which data is reproducible. If the vibration value data is smallerthan the threshold level Aa, judgment is made that reproduction at ahigher speed is possible, and a signal is sent to speed command datagenerating means 97 so as to increase the reproduction speed. In thiscase the command is for ×20 speed. In the same manner as above,vibration value data V20 at ×20 speed is compared with threshold levelBa. If vibration value data V20 is greater than the threshold level Ba,×12 speed is judged to be the maximum speed at which data isreproducible. If vibration value data V20 is smaller than the thresholdlevel Ba, judgment is made that reproduction at a still higher speed (inthis case the maximum speed is assumed to be ×24 speed) is possible.Similarly, a command signal to increase the speed is sent to speedcommand data generating means 97, and vibration value data V24 obtainedat the moment the disc has reached ×24 speed is compared with thresholdlevel Ca. If vibration value data V24 is greater than threshold levelCa, judgment is made that the disc is a vibrating disc, and a signal tolower the reproduction speed is sent to speed command data generatingmeans 97, and ×20 speed is judged to be the maximum speed at which datais reproducible. Also, while data reproduction at a further higher speedis possible if vibration value data V24 is smaller than threshold levelCa, vibration value detection is completed by judging that ×24 speed isthe maximum speed at which data is reproducible because ×24 speed is themaximum speed in this case.

Next, a description will be given on vibration data read-out process inreference to FIG. 5. Upon start of vibration detection as describedabove, vibration data read-out routine will start in the first place,and initialization of peak data is carried out. This is done by storingpositive or negative peak voltage of the TE voltage that appears duringone rotation of a disc. Data capture during one rotation is done bysuccessively sampling data from the first positive or negative peakvoltage to the next positive or negative peak voltage at appropriateintervals, and sending the result from maximum value detecting means 94in FIG. 4 to microprocessor 18M. Microprocessor 18M temporarily storesthe TE signal voltage in work RAM 18R. After data of one rotation isstored in work RAM 18R, positive and negative peak voltages are read outand the values are stored as vibration data at a separate address withinwork RAM 18R.

A description on threshold level change, being a key part of the presentinvention, will now be given below in reference to FIG. 6. In thepresent invention, it is common that allowable vibration value of adisc-shape storage medium (CD-ROM and the like) reproducer differsdepending on the product system to which the disc-shape storage medium(CD-ROM and the like) reproducer is applied, such as a portable personalcomputer in which a key board, HDD unit, display and the like areencased as an integral unit, or a desktop personal computer in whichindividually encased separate units are connected with cables.Consequently, in the manufacturing process of a disc storage media(CD-ROM and the like), the allowable vibration value, namely, thresholdlevel differs for each individual product system such as SpecificationA, Specification B, etc.

Therefore, a standard threshold level for each different specificationis burnt into EEPROM 51 (FIGS. 1 and 4) in advance as a voltage value inthe form of a 2-byte long numeral.

For example, supposing that the exemplary embodiment described above isSpecification A, as parameters for Specification A as in the descriptionin reference to FIG. 8, maximum values of the tracking error signalamplitude that correspond to the allowable-limit vibration value (0.5gram-cm, for example) of a disc-shape storage medium (CD-ROM and thelike) reproducer are burned in for an allowable-limit vibrating disc,for example, Aa for the lowest rotational speed of ×12 speed of thereproducer, Ba for medium ×20 speed, and Ca for the highest speed of ×24speed. As parameters for Specification B, maximum values of trackingerror signal amplitude that correspond to separate allowable-limitvibration values are burned in with 2-byte numerals Ab, Bb, Cc in thesame manner as above.

On the other hand, as individual disc reproducers have performancedispersion in the manufacturing process, the maximum value of trackingerror that corresponds to each of the standard threshold levelparameters at respective rotational speed varies and is measured in areproducer of Specification A, for example, to be Aa′, Ba′, Ca′: or Ab′,Bb′, Cb′ in the case of Specification B. Table 1 shows an example. Inorder that a disc reproducer can surely detect a vibrating disc anddetect the allowable maximum reproduction speed of the disc reproducer,in the event the maximum value of TE signal voltage that corresponds tothe standard threshold level parameter is different, rewriting of theEEPROM data is carried out using the maximum value of the TE signalvoltage as the threshold level.

By way of concrete examples, in Table 1, suppose that the designedcentral TE signal voltage, Ca, of a disc-shape storage medium reproducerbased on Specification A at ×24 speed is Ca=1.50 volt. If the TE signalvoltage obtained by mounting an allowable-limit disc Dc on a reproducerbeing manufactured is 1.60 volt, rewriting of the threshold level is notnecessary.

TABLE 1 Spec A reproducer Spec B reproducer Std Std Disc thresholdMeasured threshold Measured rotational level tracking level trackingspeed parameter error parameter error X12 speed Aa Aa′ Ab Ab′ X20 speedBa Ba′ Bb Bb′ X24 speed Ca Ca′ Cb Cb′

The reason is because, as the TE signal voltage is greater than thethreshold level, a disc having a vibration value greater than that ofthe allowable-limit disc will be reproduced at a lowered speed thusvibration will not increase.

However, when the TE voltage is 1.45 volt, there may occur a case wherethe TE signal voltage is 1.50 volt or smaller even when a disc with alarger vibration value than the allowable-limit disc is mounted andreproduced. In such a case, unless the threshold level is rewritten,vibration will increase. By rewriting the threshold level, reproductionat the maximum speed is enabled as close to the allowable vibrationlimit as possible, and data read-out at a high speed is enabled. Whenthe threshold level is set at 1.20 volt, for example, TE signal voltageof majority of discs will be 1.20 volt or greater, and there will belittle possibility of being able to read out data at the maximum speed.

Next, when the vibration value data of an allowable-limit disc Dc at ×20speed is Ba′, judgment is made on the standard threshold level Ba in thesame manner.

By correcting dispersions of individual disc reproducers in the mannerdescribed above, an accurate discrimination as to whether or notvibration value of a disc in general with an unknown mass eccentricityis within the allowable limit is enabled.

When the change mode is “Yes” under this condition, microprocessor 18Mcaptures the vibration value that is measured to be the maximum value ofthe TE signal, and changes standard value data Ca burned in EEPROM 51 tothreshold level Ca′ that is peculiar to the reproducer in question thusaccomplishing vibration detection threshold level changing process.Subsequently, when the vibration value data of the allowable limit discDc at ×20 speed is Ba′ and the change mode is “Yes”, a process iscarried out to change the standard data Ba to peculiar threshold levelBa′ in the same way. Subsequently, if the vibration value data of anallowable-limit disc Db at ×12 speed is Aa′ and the change mode is“Yes”, a process is carried out in the same way to change the standarddata Aa to threshold level Aa′ that is peculiar to the reproducer inquestion.

Further examples of above method of increasing detection accuracy byincreasing the number of vibration detection and judgment will bedescribed below.

When data reproduction speeds of a data reproducer are ×10 speed, ×20speed, ×30 speed, and ×40 speed, by setting vibration detecting speedsas shown in Table 2 and increasing the number of vibration judgment, themaximum reproduction speed of a disc with further smaller vibrationvalue (0.3 gram-cm, for example) can be judged with high accuracy.Furthermore, by providing two threshold levels Ac1, Ac2 for vibrationdetection, it becomes possible to prevent possibility of a disc with alarge vibration value (1 gram-cm, for example) to vibrate to an extentdiscernible by a user even at ×20 speed, and to prevent abandoning of asituation in which little vibration occurs at ×20 speed with a dischaving a small vibration value (0.3 gram-cm, for example), namely,abandoning of possibility of reproduction at a higher speed.

TABLE 2 Specification C Specification A Estimated Threshold MeasuredThreshold Measured threshold level value level value level change X12 AaAs′ Ac1 Ac′ Ac′ speed Ac2 Ac′ + α1 X20 Ba Ba′ Bc1 Bc′ Bc′ speed Bc2Bc′ + α2 X24 Ca Ca′ Cc1 Cc′ Cc′ speed Cc2 Cc′ + α3

In summary, reduction in system functionality due to reproduction of adisc with a small vibration value at a low speed can be lessened byreproducing a disc with a large vibration value (Ac′>Ac2) at a lowspeed, and reproducing a disc with a small vibration value (Ac1<Ac′<Ac2)at a medium speed.

Here, the estimated threshold level change is a change of the value thatis judged to be needed when the measured value is for a standard disc,and α1, α2, α3 are values for correction equal to the distance betweentwo threshold levels.

A further detailed description will now be given below in reference toFIG. 9. FIG. 9 shows relationship between speed of vibration detectionand vibration value produced. Curves A, B, C, D, E represent speed vs.vibration value characteristic for each of standard discs that generatesallowable-limit vibration value at the speed of vibration detection. Asshown in the figure, threshold levels can be set as threshold levelsAc1/Ac2 for ×12 speed, threshold levels Bc1/Bc2 for ×20 speed, thresholdlevels Cc1/Cc2 for ×24 speed, . . . , and threshold levels Ec1/Ec2 for×40 speed.

These cases include cases where the data reproduction speed andvibration detecting speed are different. For example, when vibrationdetection of a disc with an unknown vibration value is started,vibration is detected at ×12 speed that is the lowest of the vibrationdetecting speeds. If vibration value Ac′ satisfies Ac′>Ac2, the disc isjudged to be a vibrating disc, and the data reproduction speed isdetermined to be ×10 speed. If A1<Ac′<Ac2, ×10 speed is determined to bethe data reproduction speed as this speed is not a data reproductionspeed.

If Ac′<Ac1, judgment is made that data reproduction at a higher speed ispossible, and vibration measurement is carried out by increasing thereproduction speed to ×20 speed which is the next vibration detectingspeed. The relationship between threshold levels Bc1, Bc2 at this speedand the obtained vibration value Bc′′is then judged. This case beingdata reproduction speed, the maximum data reproduction speed will be ×10speed if Bc′>Bc2 and ×20 speed if Bc1<Bc′<Bc2. Also, if Bc′<Bc1,judgment is made that maximum data reproduction speed for datareproduction exists on even higher speed side, vibration detection iscarried out by increasing the reproduction speed to ×24 speed, and therelationship with threshold levels Cc1, Cc2 is judged. When maximumspeed of ×40 speed is reached by successively repeating this process,detected vibration value Ec′ (of a disc with a small vibration value) iscompared with threshold level Ec1 (≈Ec2) and judged in the same manneras above.

As ×40 speed is the maximum speed for data reproduction in this case, ifEc′<Ec1, then Ec1<Ec1′<Ec2, and ×40 speed is judged to be the maximumdata reproduction speed. If Ec′>Ec2, then ×30 speed is judged to be themaximum data reproduction speed and vibration detection is completed.

Next, EEPROM 51 for storing threshold levels will be discussed. Onepossible embodiment is to incorporate EEPROM 51 in the so-called IC card151 so that IC card 151 can be inserted into slot 150 provided on ahousing of a disc reproducer 2 as illustrated in FIG. 7. In this case,as a different threshold level is stored in EEPROM 51 for each differentspecification, it gives convenience in manufacturing mixed models on asingle production line. The same advantage may be obtained by providingslot 152 for the IC card on a housing of host computer 1. In this case,needless to say, threshold level and vibration value are compared afterreproducer 2 has been inserted into reproducer slot 122 of host computer1, threshold level is set based on the measured result, and reproducer 2is kept inserted in host computer 1 once setting has been made. In FIG.7, numeral 121 is a slot for a floppy disc and numeral 123 is a displayof host computer 1.

As has been described above, the present exemplary embodiment has thefollowing advantages.

(1) As the amount of eccentricity is measured and rotational speed of

disc 4 is determined prior to data reproduction, occurrence of a dataread-out error due to a tracking error that occurs after start of datareproduction can be avoided, and overall reduction in data reproductionspeed can be avoided. Even if reproduction is made at the maximum speed(first speed) from the beginning, if an error occurs, the time requiredfor reproduction will become long in the end due to retrials and thelike. Conversely, in this exemplary embodiment, the maximum speed atwhich stable data reproduction is possible can always be determined atbelow the vibration value that is acceptable by a reproducer by carryingout detection of vibration value on the low speed side using a pluralityof threshold levels that have been set. As a result, data reproductionis enabled without giving unpleasant feeling to a user, occurrence oferror is reduced, and required reproduction time is made shorter thanwhen an error is occurring.

(2) In this exemplary embodiment, a description is made on detection

of vibration of a reproducer due to a disc with mass eccentricity as theamount of eccentricity of a track in terms of a tracking servo errorsignal. However, similar concept can be applied to a system in whichvibration is detected in the form of a signal that crosses the trackobtained by making the tracking servo system open. It is also applicableto a system in which vibration of a reproducer is detected with anacceleration sensor.

(3) The advantages of (1) and (2) above also apply to a recording deviceof

a recordable disc-shape storage medium in which allowable vibration ofthe device is severer, and further enhanced advantage will be exhibited.

(4) In the case of a low quality disc, as rotational speed is not madehigh,

vibration of disc 4 and a disc reproducer as a whole is suppressed, andinfluence of vibration on other devices (such as HDD) is lessened. Also,as vibration is reduced, unpleasant feeling to a user is reduced.

Industrial Applicability

By setting an amount of allowable vibration of a disc-shape storagemedium reproducer-recorder by using a disc having a known masseccentricity, data reproduction is enabled by rotating a disc at themaximum speed that can be set while keeping the vibration value producedwithin an allowable limit when discs with different mass eccentricityare reproduced or recorded.

List of Reference Numerals

1. Host personal computer

2. Disc-shape storage medium reproducer

3. Bus line

4. Disc recording medium (CD-ROM and the like)

5M. Spindle motor

5D. Spindle driver

5F. FG signal

5S. One rotation periodic signal

6. Optical pickup

7. Pickup drive

8. Waveform-shaping circuit

9. Servo processor

10. Error correction/interface circuit

11. System control block

12. Spindle servo block

13. Pickup servo block

13T. Tracking servo block

14. Synchronization detection and demodulation circuit

15. Interface for microprocessor

16. 16. Error detection and correction circuit

17. Interface circuit

18M. Microprocessor18P. Program ROM

18R. Work RAM

18C. Clock generator

19. Spindle

20. Center hole

30, 33. Phase compensation and drive circuit

31. TE detecting circuit

32. Focus error detecting circuit

34. Data detecting circuit

36. TE signal

36T. Digitalized TE signal

41. Track

42. Spot

51. EEPROM

52. Writing/reading control means

61. Laser beam

62. Diffraction grating

63. Cylindrical lens

64. Reflected light beam

65. Beam splitter

66. Collimater lens

67. ¼ wavelength plate

68T. Tracking actuator

68L. Objective lens

69, 69F, 69B. Optical detector

90. Vibration value detecting and judging means

91. A/D converter

92. Maximum-value detecting means

93. Frequency divider

94. Comparing means

95. Threshold level generating means

96. Mode switching signal generating means

97. Speed command data generating means

98. Line

121. Floppy disc slot

122. Reproducer receiving slot

123. Display

141, 150, 152. Receiving slot

151. IC card.

What is claimed is:
 1. A disc-shape storage medium reproducercomprising: disc rotating means for rotating a storage medium dischaving data recorded on a spiral or concentric tracks and having acenter hole, said disc rotating means including a spindle to be insertedinto said center hole, and being formed in a manner such that said disccan be detachably inserted and that the rotational speed can be varied;a signal converter for reading out said data from said disc; movingmeans for moving said signal converter in radial direction of said disc;wherein values relating to vibration values that are measured withvibration value measuring means by mounting a disc (allowable-limitdisc) with a known mass eccentricity into said reproducer and rotatingsaid allowable-limit disc are stored in storage means inside saidreproducer as a threshold level that indicates the allowable limit. 2.The disc-shape storage medium reproducer of claim 1, wherein storedcontent of said storage medium disc is rewritable.
 3. The disc-shapestorage medium reproducer of claim 1, wherein reading out and rewritingof the content of said storage medium disc are possible.
 4. Thedisc-shape storage medium reproducer of claim 1, wherein a storagemedium disc is mounted on a disc-shape storage medium reproducercomprising rotation control means which is settable to n kinds of datareproducing speeds and at least n kinds of vibration detecting speedsincluding said reproducing speeds, the vibration value of said disc ismeasured by rotating said disc at a vibration detecting speed lower thanthe maximum reproducing speed, and the maximum reproducing speed atwhich data is reproducible is determined based on judgment on at least npieces of threshold levels that have been set based on theallowable-limit vibration value that is preset in said reproducer. 5.The disc-shape storage medium reproducer of claim 1, wherein a pluralityof threshold levels corresponding to a plurality of allowable-limitdiscs is stored in a nonvolatile memory.
 6. The disc-shape storagemedium reproducer of claim 1, wherein a nonvolatile memory storingthreshold levels is incorporated in an IC card (memory card) and saidmemory card is detachable from outside said reproducer.
 7. Thedisc-shape storage medium reproducer of claim 2, wherein a storagemedium disc is mounted on a disc-shape storage medium reproducercomprising rotation control means which is settable to n kinds of datareproducing speeds and at least n kinds of vibration detecting speedsincluding said reproducing speeds, the vibration value of said disc ismeasured by rotating said disc at a vibration detecting speed lower thanthe maximum reproducing speed, and the maximum reproducing speed atwhich data is reproducible is determined based on judgment on at least npieces of threshold levels that have been set based on theallowable-limit vibration value that is preset in said reproducer. 8.The disc-shape storage medium reproducer of claim 2, wherein a pluralityof threshold levels corresponding to a plurality of allowable-limitdiscs is stored in a nonvolatile memory.
 9. The disc-shape storagemedium reproducer of claim 2, wherein a nonvolatile memory for storingthreshold levels is incorporated in an IC card (memory card) and saidmemory card is detachable from outside said reproducer.
 10. Thedisc-shape storage medium reproducer of claim 3, wherein a storagemedium disc is mounted on a disc-shape storage medium reproducercomprising rotation control means which is settable to n kinds of datareproducing speeds and at least n kinds of vibration detecting speedsincluding said reproducing speeds, the vibration value of said disc ismeasured by rotating said disc at a vibration detecting speed lower thanthe maximum reproducing speed, and the maximum reproducing speed atwhich data is reproducible is determined based on judgment on at least npieces of threshold levels that have been set based on theallowable-limit vibration value that is preset in said reproducer. 11.The disc-shape storage medium reproducer of claim 3, wherein a pluralityof threshold levels corresponding to a plurality of allowable-limitdiscs is stored in a nonvolatile memory.
 12. The disc-shape storagemedium reproducer of claim 3, wherein a nonvolatile memory for storingthreshold levels is incorporated in an IC card (memory card) and saidmemory card is detachable from outside said reproducer.
 13. Thedisc-shape storage medium reproducer of claim 4, wherein a plurality ofthreshold levels corresponding to a plurality of allowable-limit discsis stored in a nonvolatile memory.
 14. The disc-shape storage mediumreproducer of claim 4, wherein a nonvolatile memory for storingthreshold levels is incorporated in an IC card (memory card) and saidmemory card is detachable from outside said reproducer.
 15. A disc-shapestorage medium reproducer comprising: disc rotating means for rotating astorage medium disc having data recorded on spiral or concentric tracksand having a center hole, said disc rotating means including a spindleto be inserted into said center hole and being formed in a manner suchthat said disc can be detachably inserted and that the rotational speedcan be varied; a signal converter for reading out said data from saiddisc; moving means for moving said signal converter in the radialdirection of said disc; vibration value measuring means for measuringvibration obtained by rotating said disc; storage means for storing datarelating to allowable-limit vibration value as threshold level;comparing means for comparing said threshold level with the datarelating to the vibration value measured by said vibration valuemeasuring means; and judging means for judging whether or not said datarelating to the measured vibration value is within an allowable rangeset by said threshold level; wherein the data relating to said allowablevibration-limit value is stored in advance in said storage means as athreshold level for criterion, said threshold level for criterion iscompared by said comparing means with the data relating to the vibrationvalue obtained by rotating said allowable-limit disc using a disc with aknown mass eccentricity as an allowable-limit disc, and when judgment ismade by said judging means that the vibration value is outside theallowable range, said threshold for criterion is changed.
 16. Thedisc-shape storage medium reproducer of claim 15, wherein the storedcontent of said storage medium disc is rewritable.
 17. The disc-shapestorage medium reproducer of claim 15, wherein reading out and rewritingof the stored content of said storage medium disc are possible.
 18. Thedisc-shape storage medium reproducer of claim 15, wherein a storagemedium disc is mounted on a disc-shape storage medium reproducercomprising rotation control means which is settable to n kinds of datareproducing speeds and at least n kinds of vibration detecting speedsincluding said reproducing speeds, the vibration value of said disc ismeasured by rotating said disc at a vibration detecting speed lower thanthe maximum reproducing speed, and the maximum reproducing speed atwhich data is reproducible is determined based on judgment on at least npieces of threshold levels that have been set based on theallowable-limit vibration value preset in said reproducer.
 19. Thedisc-shape storage medium reproducer of claim 15, wherein a plurality ofthreshold levels corresponding to a plurality of allowable-limit discsis stored in a nonvolatile memory.
 20. The disc-shape storage mediumreproducer of claim 15, wherein a nonvolatile memory for storingthreshold levels is incorporated in an IC card (memory card) and saidmemory card is detachable from outside said reproducer.